Cookie information

We have placed cookies on your computer to help make this website better. You can change the cookie settings at any time. Otherwise, we’ll assume you’re OK to continue. For details on how Castrol treats your personal information, please see our privacy policy

ENGINE OIL

What is engine oil?

The primary function of modern-day engine oil is to lubricate and protect the moving parts within an engine to ensure optimal performance and longevity.

Engine oil was historically a mixture of mineral base oil and additives used to reduce friction between moving engine parts, however with advances in modern technology many engine oils can also be created with synthetic, chemical compounds.

HOW DOES ENGINE OIL WORK?

Engine oil begins its journey in the engine's sump, which is the reservoir of oil. From here it gets pumped around the engine by the vehicle's oil pump.

The oil pump is vital to the life of the engine. It sucks oil up from the sump through a pickup tube, pressurises it, and sends it through the entire engine through a circuit of oilways.

From the pump, the oil travels to the oil filter, which removes microscopic particles and supplies clean oil to the rest of the engine.

Key parts of the engine, such as bearings, pistons and valve-train all benefit from engine oil cleaning, lubricating and protecting.

WHAT DOES THE OIL IN MY CAR DO?

Using the correct oil keeps an engine running smoothly. It creates a thin, lubricating layer between metal surfaces, which stops them from grinding against each other and becoming worn or damaged.

Oil also prevents corrosion, cools the engine and helps keep the engine clean and protected.

WHAT IS ENGINE OIL TYPICALLY MADE OF?

Engine oil typically consists of about 80% base oil and 20% performance additives. The performance additives include anti-wear additives, antioxidants, dispersants and detergents that keep the engine clean, and viscosity index improvers that ensure the oil maintains an optimum viscosity throughout the engine’s operating temperature range.

The base oil carries these additives to where they are needed, and provides vital cooling to engine components, by drawing away heat. Base oils can be either mineral or synthetic, and engine oils can contain all mineral base oil, all synthetic base oil, or a mixture of the two. Engine oils containing a mixture are typically described as semi synthetic or part synthetic.